J. Y.Lewis — Palisade Diabase of New Jersey. 159 



quartz-diabase, and this becomes slightly olivinic near the con- 

 tacts. 



In the quantitative system of Messrs. Cross, Iddings, Pirs- 

 son, and Washington the analyses given above would be clas- 

 sified as follows : 



I. Class II. Dosalane 



Order 4. Quardofelic, Austrare 

 Rang 2. Domalkalic, Dacase 



Subrang 4, Dosodic, Dacose 

 II. Class II. Dosalane 



Order 4. Quardofelic, Austrare 

 • Rang 3. Alkalicalcic, Tonalase 



Subrang 4. Dosodic, Tonalose 



III. Class III. Salfemane 



Order 5. Perfelic, Gallare 



Rang 3. Alkalicalcic, Camptonase 

 • Subrang 4. Dosodic, Camptonose 



IV. Class IV. Dofemane 



Order 1. Perpolic, Hungarare 

 Section 2. Dopyrie 



Rang 1. Permirlic 



Section 2. Domiric 



Subrang 2. Domagnesic, Palisadose 



The great bulk of the rock, judging from about a dozen 

 analyses and a large number of thin sections, appears to be of 

 the type represented by the third of the analyses given above, 

 and might be termed a graphi-ophito- to graplii-grano-camp- 

 tonose (III. 5. 3. 4). Notable amounts of the rock, however, 

 belong to the more salic dacose (II. 4. 2. 4) and tonalose (II. 

 4. 3. 4) and to the more calcic auvergnose (III. 5. 4. 4, 5). 



The highly basic ferromagnesian olivine-diabase, of which 

 the fourth analysis above is typical, is a sharply defined facies 

 that may be designated as a poikili-opkito- to poikili-grano-pali- 

 sadose. From the typical development of this rock along the 

 Palisades northward from Jersey City it is proposed that the 

 subrang into which it falls (IV. I 2 . V. 2), hitherto unnamed, 

 be designated as palisadose. 



The relations of these various facies to each other and the 

 problem of their origin are discussed in the report on the 

 petrography of the Newark igneous rocks of New Jersey.* It 

 has already been remarked that the hypothesis of gravitational 

 differentiation seems to account satisfactorily for all the condi- 

 tions observed. 



Composition of the Augite. — Analyses of the augite from 

 this sill at Rocky Hillf and from the very similar intrusive at 

 West Rock, New Haven, Conn., J yielded the following results : 



* Annual Report of the State Geologist of New Jersey for 1907. 



\ A. H. Phillips, loc. cit. 



\ G. H. Hawes, this Journal, vol. ix, p. 185, 1875. 



